id --version (return code: 0)
id (GNU coreutils) 8.25
Copyright (C) 2016 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>.
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.
Written by Arnold Robbins and David MacKenzie.
id --help (return code: 0)
Usage: id [OPTION]... [USER]
Print user and group information for the specified USER,
or (when USER omitted) for the current user.
-a ignore, for compatibility with other versions
-Z, --context print only the security context of the process
-g, --group print only the effective group ID
-G, --groups print all group IDs
-n, --name print a name instead of a number, for -ugG
-r, --real print the real ID instead of the effective ID, with -ugG
-u, --user print only the effective user ID
-z, --zero delimit entries with NUL characters, not whitespace;
not permitted in default format
--help display this help and exit
--version output version information and exit
Without any OPTION, print some useful set of identified information.
GNU coreutils online help: <http://www.gnu.org/software/coreutils/>
Full documentation at: <http://www.gnu.org/software/coreutils/id>
or available locally via: info '(coreutils) id invocation'